I agree with you, and incidentally so does Gerald Sussman (co-inventor of Scheme). He helped write an entire book on Lagrangian mechanics that uses Scheme because he believes the math notation is too fuzzy and confusing for people.
Both this and the subsequent text on differential geometry are very good but they are written against this enormous undocumented scheme library (scmutils) that is in my opinion very difficult to debug or figure out how macros expand out.
https://mitpress.mit.edu/sites/default/files/titles/content/...